Online Abacus and Abacus Lessons
Slide the beads to count, and learn tens and ones, addition and subtraction step by step.
An abacus teaches counting and arithmetic by sliding beads along rods. This one is the school counting frame: ten rods with ten beads each — five red and five natural — one hundred beads in all.
Tap the beads above to count freely. If this is your first time, start with the step-by-step lessons: each step tells you what to do and moves on when you get it right. Then test yourself with random questions in the Practice tab.
How to use it
- Beads resting on the left are not counted. Tap a bead to slide it to the right and count it.
- The beads to the right of the one you tap slide with it, so one tap on the fourth bead from the right makes 4.
- Tap a counted bead to slide it back. Press Clear to return everything.
- The number beside each rod shows how many beads are counted on it; the large number above shows the total.
- In the lessons, use Hint or Show me if you get stuck.
What is a counting-frame abacus?
It is a frame with ten rods and ten beads on each rod. Because all one hundred beads are in view, children learn counting, tens and ones, addition and subtraction by seeing them rather than memorising.
Five beads on each rod are red and five are natural. The colours let you recognise five at a glance: five natural beads on the right are 5; with two red ones beside them, 7.
How numbers are shown
For numbers up to 10, slide that many beads to the right on the top rod. Beyond 10, read full rods as tens and the partly filled rod as ones: 47 is four full rods and seven beads on the fifth.
How to add and subtract
Adding is sliding more beads across. When a rod runs out, make ten first: for 8 + 5, slide the last 2 beads on the top rod, then 3 on the next — 8 + 2 = 10, 10 + 3 = 13.
Subtracting is sliding beads back. When the partly filled rod is not enough, break a ten: for 13 − 5, slide back the 3 on the second rod, then 2 more from the top rod.
Frequently Asked Questions
At what age can children use an abacus?
Children who enjoy counting can play with it from age three or four. Tens and ones, addition and subtraction are usually practised between five and seven.
Why are the beads two colours?
Five red and five natural beads on each rod let you see 5, and numbers above 5, at a glance without counting one by one.
How is this different from a Japanese soroban?
On a counting frame every bead is worth 1 and numbers up to 100 are shown; it teaches what the operations mean. On a soroban each rod is a place value and the upper bead is worth 5; it is used for fast calculation with large numbers.